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Old 30-10-2018, 10:42 AM
Jethro777 (Jethro)
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Budget DSLR Astrophotography - Equipment First Steps

After playing with the idea of telescopes, the reality dawned that the budget simply didn't allow it.
Instead, I decided to stop admiring images taken with others equipment and find joy with what I do have, and getting the best out of that.
I do have some nice equipment thus far:

- Sony Alpha A77

Some nice Lenses:

- Samyang 35mm f/1.4
- Minolta AF 24mm 2.8
- Minolta AF 100 Macro 2.8
- Sony DT 35mm 1.8 (In poor condition)

I suspect I could do a but with that.

I just have a terrestrial tripod, nothing too fancy, I have no star tracker, and so am limited to that equipment.

I can learn how to stack images, and take some photos.

What do you guys think? If you were to invest in something (why not, I'll save for something!) what should it be? A star tracker like the iOptron or Vixen Polarie? A proper mount?

Love to hear your thoughts!
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Old 30-10-2018, 11:25 AM
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How about DIY barn-door mount?

It would be quite adequate for 100mm lens.

Last edited by bojan; 30-10-2018 at 11:37 AM.
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Old 30-10-2018, 11:59 AM
Jethro777 (Jethro)
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That sounds like a great project!
I like it.

I found this : https://barn-door-tracker.co.uk/
This looks pretty good.
I should add I'm not much of a machinist or engineer, but I'm always up to learning or trying something new.

I'm in Brisbane, if someone here has built one, and knows where to get the bits and pieces, that would help me a lot later.

Last edited by Jethro777; 30-10-2018 at 12:22 PM.
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Old 30-10-2018, 12:29 PM
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Bunnings rules ....
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Old 30-10-2018, 12:58 PM
Jasp05 (Aaron)
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I started in exactly your position. Minimal funds to get into the hobby. I owned a DSLR and a few lenses. Started taking long exposure from a static tripod. (up to 20sec exposures).

I built a Barn door tracker and powered it with an arduino and stepper motor.
This produced some half decent results although my polar alignment was never great. (Pics of my first images with the barn door tracker attached.) I posted these pics on the forums and here is the link for details.

http://www.iceinspace.com.au/forum/s...d.php?t=157418


I've since upgraded to an HEQ5Pro mount and not looked back.

The hardest thing is to know how far you want to go with this hobby. If your only interested in widefield imaging then something like a Star adventurer mount for $400-$500 would be the way to go. (I'm still considering getting one for portability over the heq5).

If you are going to get more serious in the future then a HEQ5pro or better mount will probably be needed.


But I'd definately start at the barn door tracker. It's simple and costs about 20 bucks and a few hours to make.

This is a calculator to help you work out rotations per minute etc depending on threads per inch. https://blarg.co.uk/astronomy/barn-d...ker-calculator.
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Old 30-10-2018, 04:13 PM
Hoges (John)
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I can't remember if this worked - I don't think it was very good. But it was a lot of fun to build. Sorry I don't have any shots of the drive mechanism but it was a little 12v motor. Barn Doors are suppose to be agricultural aren't they?
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Old 30-10-2018, 04:22 PM
RyanJones
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Hi Jethro,

Yeah, you're right, there's no such thing in this game as budget. Having said that, your first paragraph made me smile, making the best of what you've got. I started in humble beginnings and quite honestly, I'm still there. I just purchased a faster scope and, in a couple of hours in a dark site, took photos that would take me 3 or 4 sessions to produce at home. Call me a masacistic but I actually felt a little disappointed that it was so easy. If you like a challenge and genuinely want to the make the best of what you've got then a cheap mount ( alt-az with a wedge ) and a cheap scope. If you want to do it like the other guys on here then save your pennies. Fair go which ever way you go but be prepared for a very expensive addiction. ( relatively speaking )
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Old 30-10-2018, 09:15 PM
ripsnorter63 (Craig Spry)
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I've just built a barn door tracker and I used ebay to get the extra tripod head and remote shutter release. I found some old floor board and various nuts in my extensive collection of nuts and bolts that will come in useful one day. M6 threaded rod and hinge came from my local hardware shop. Mine is wound by hand at the moment and I really just threw it together to see if it would work. It seems to work so I'm going to start work on the next version with a better handle and some marking lines so I can more accurately turn the handle, right now I'm using the beeps from my remote shutter release and counting to 15 and moving the handle what I think is 90 degrees in that time.
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Old 31-10-2018, 11:03 AM
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Quote:
Originally Posted by RyanJones View Post
Hi Jethro,
Fair go which ever way you go but be prepared for a very expensive addiction. ( relatively speaking )
Yes be careful what you wish for. Expanding the Definition of Addiction: DSM-5 vs. ICD-11
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5328289/
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Old 31-10-2018, 11:25 AM
Saturnine (Jeff)
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Barn Door trackers are a relatively cheap , simple solution to being able to do longer exposure images, 30 to 60 sec is enough when also stacking several ( or many ) together. Made myself one last year , though it is a bit more high tech, as it is powered by an 12VDC Geared Motor.
Guess I'm a bit fortunate in that I was a Fitter & Machinist by trade, now retired and still have access to a lathe and milling machine. Did some basic math for the curvature of the 6mm x 1mm pitch, threaded rod, motor speed and gear ratio vs the distance from the hinge to the threaded rod ( radius of curvature ) to achieve the desired tracking rate.
Speed is not perfect, is out by about 1 deg. an hour which equates to 1 arc/ min for an 60 sec exposure. for wide angle lens is hardly noticeable.
Intend to add an PWM unit to fine tune the speed for greater tracking accuracy soon but I'm happy with the results so far.
All up the bits and pieces cost about $30, motor , ball head , hinge, paint etc. and machined the pulleys to suit with an "o" ring as the drive belt. Had some aluminium plate already but wood can be used quite successfully .
Polar alignment is achieved by mounting an old finder scope butted against the hinge, held by an elastic band and pointing at Sigma Octans and offsetting the required distance to the SCP.
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Old 31-10-2018, 01:52 PM
Jethro777 (Jethro)
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Really enjoying your thoughts and pics of your home projects. Nice!

So - this one looks pretty good, https://barn-door-tracker.co.uk/

(Reason I like this one, is because for a non-technical guy, I like fixed measurements and instructions. )

If I wanted to make an Aussie version, would that hinge be the right way? (No Polaris, Southern Hemisphere).

Might go to some fleamarkets and see what bits I can get.
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Old 31-10-2018, 02:07 PM
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Merlin66 (Ken)
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I made a double arm Trott barn door tracker a few (?!) years ago....
standard aluminium sections and a quick release nut.
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Old 31-10-2018, 03:44 PM
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silv (Annette)
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I remember I spent NZD 200 on all new materials including all new tools (didn't have any, not even a screwdriver) I needed for a wooden BDT almost like your favorite in your link there. It worked, sort of. Wasn't precise enough to give me more than 12 secs with a 200mm lens. Was my first ever DIY product. So I was proud nevertheless.
Not being gifted with imagination in mechanics, I then proceeded to build another out of colourful ~8mm plastic cutting boards, thinking it'd be more lightweight than the rather heavy wooden version and fit better on my plastic $50 tripod. It did look real cool. But it was too floppy for the heavy camera
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Old 31-10-2018, 04:26 PM
Jethro777 (Jethro)
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Quote:
Originally Posted by silv View Post
I remember I spent NZD 200 on all new materials including all new tools (didn't have any, not even a screwdriver) I needed for a wooden BDT almost like your favorite in your link there. It worked, sort of. Wasn't precise enough to give me more than 12 secs with a 200mm lens. Was my first ever DIY product. So I was proud nevertheless.
Not being gifted with imagination in mechanics, I then proceeded to build another out of colourful ~8mm plastic cutting boards, thinking it'd be more lightweight than the rather heavy wooden version and fit better on my plastic $50 tripod. It did look real cool. But it was too floppy for the heavy camera
Awesome story.

Thanks for sharing your experience!
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Old 31-10-2018, 04:51 PM
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silv (Annette)
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Story continues.
Not having succeeded (enough) with my BDT, I then went over to the dark side and spent $$$ on 2nd hand gear. I really really really wanted my backyard Hubble telescope photos. And I wanted them NOW.

The only affordable set on Trademe then was an EQ5 Goto with retrofitted GotoNova handcontroller (now iOptron) and an 8" newton. NZD 1000. The owner had used it for visual and that had worked for him. I took it home, got familiar with the scope tech and the weight... 8kg was the scope, I remember, all included (tube rings, finder, focuser).
On an EQ5... 'nough said.

Or not?

Well. My camera, mounted piggy back onto the scope, certainly gained exposure time before star trailing. 2 minutes at ~18-55mm was no problem. But the motor and the stability of the EQ5 didn't appreciate being ridden by an 8kg ~1m long tube with the majority of the weight being far away from the tripod, and reasonably heavier at the very top end of the tube.
So the 20 secs exposures I took in prime focus = camera mounted onto the focuser, all showed dips in very regular intervals. As if jumping from one little tooth to the next was heavy duty for the little wheels inside. Broke my heart.

The mount's load capacity for visual must have been something between 9 and maybe 12kg. Half that weight in a scope would have been proper astrophotography standards. I did know that from reading threads on iceinspace. But I felt that wouldn't apply to me. Like with cancer from smoking. It only ever happens to others.
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Old 31-10-2018, 05:08 PM
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That was all in 2012. Sold on the mount and scope the same year. Stopped taking photos of the night sky, except some [beautiful] aurora photos when I lived on the S.I.

Yesterday, a new iOptron CubePro II magically arrived at my doorstep. Not intended for astrophotography, only for visual to carry a 2nd hand "fast" refractor 102/500mm, f/4.9 It's a good thing that I now live in a Bortle 6-7 area and I know I can't and I won't afford gear capable of gathering meaningful photons from here. But I conjured up a cheap binoviewer as well. So am very much looking forward to "grazing" up and down the milky way here in my western sky . 'Cause that's what I enjoyed the most, really, back in 2012: spending time with my eyes and mind in the ocean of stars.
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Old 31-10-2018, 10:20 PM
Jethro777 (Jethro)
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"First Light" - DSLR Only

Well,

I took the camera for a spin to see what it could do to start with.

I shot Mars and surrounding stars

Tripod Only - No Tracker of any sort
2 second delay, remote shutter on concrete

First Set
High ISO Adjust
1600 ISO
15 second exposure
F/8

Second Set
Low ISO Adjust
1600 ISO
13 Second Exposure
F/8


Third Set
1000 ISO
10 Second Exposure
F/1.4

Camera is a Sony SLT-A77 with a Samyang 35mm f/1.4 lens.
I live in a fairly light polluted area, shooting from the backyard.
I used Long Exposure NR Reduction on the camera.
ISO adjustment LOW. (only has low, medium, high).

I took from between 6-9 images, and used DSS to stack them using just the default settings. No use of dark files, flat files, dark flat files or offset/bias files (no idea what they mean yet).

I have attached a small 100% size cut of the imaging.

Some questions:

When I used the RAW pictures I took, DSS barely recognised many stars. When I used the camera processed JPEGS, it recognised hundreds.
DSS Scored my final pic 4326.51, then threw it down to 827 when I changed the aperture to 1.4 lol.

What can help me improve?
How many pictures might it be good to have in a stack, realistically?
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Old 01-11-2018, 06:07 AM
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Do not use long exposure compensation - separate master dark is better from SNR point of view.
And do not use jpg for stacking - lot of information is lost with conversion, especially where you do not want - at the low intensity level..
The difference in number of stars comes from the fact RAW is 16-bit, and jpg is-8-bit deep.



I am usually taking 16 or 32 frames for stacking.
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Old 01-11-2018, 06:49 AM
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Originally Posted by Jethro777 View Post
Third Set
1000 ISO
10 Second Exposure
F/1.4

Camera is a Sony SLT-A77 with a Samyang 35mm f/1.4 lens.

......

What can help me improve?
Hi J,
That lens is best used around f/4- f/5.6, but probably OK down to f/2 to f/2.8. An aperture of f/1.4 is too wide open for that lens (and most others) without significant image penalties. If you have the non-autofocus version then look to these data as the justification for this:
https://www.lenstip.com/297.4-Lens_r...esolution.html

Bear in mind however; the Samyang 35mm f/1.4 is a full-Frame lens and you are using it on the APS-c sensor of the Sony A77. It behaves like a 50mm f/2 in that respect. The APS-c sensor doesn't see all of the full frame image circle and as a result the image quality may not be as degraded at f/1.4 as it would be on a full frame camera. Of course the light collection would be doubled on fullframe and hence the noise less but, you're not concerned of that here.



Best
JA

Last edited by JA; 01-11-2018 at 07:07 AM.
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Old 01-11-2018, 07:22 AM
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Originally Posted by JA View Post
...
Bear in mind however; the Samyang 35mm f/1.4 is a full-Frame lens and you are using it on the APS-c sensor of the Sony A77. It behaves like a 50mm f/2 in that respect. The APS-c sensor doesn't see all of the full frame image circle and as a result the image quality may not be as degraded at f/1.4 as it would be on a full frame camera. Of course the light collection would be doubled on fullframe and hence the noise less but, you're not concerned of that here.
Best
JA

Hmm.. not quite like that.
Full frame lens used with APS sensor will collect exactly the same amout of light, and it will still be 35mm FL..

Difference will be in FOV - with APS sensor, fileld will be smaller, but this will not be an issue because image quality in FF corners is probably not great, so you woul want to crop it anuway (and APS sensor does it for you :-) )
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